Showing papers in "African Journal of Aquatic Science in 2010"
TL;DR: Assessment of aquatic invertebrates in the Wit River, Sundays River catchment, Eastern Cape, South Africa, was undertaken to assess the impact of the alien fish Micropterus salmoides on their relative abundance and community structure, suggesting that the presence of M. salmoide does have an impact on indigenous macroinvertebrate fauna and communities.
Abstract: Fish predation is one of the driving forces of freshwater invertebrate community structures, with alien predators having a pronounced effect. A quantitative assessment of aquatic invertebrates in the Wit River, Sundays River catchment, Eastern Cape, South Africa, was undertaken to assess the impact of the alien fish Micropterus salmoides on their relative abundance and community structure. Communities in the stones-in-current and marginal vegetation biotopes were sampled in the presence and absence of M. salmoides in late summer (February–April) 2008. Results suggest that the presence of M. salmoides does have an impact on indigenous macroinvertebrate fauna and communities. Community structure in the stones-in-current biotopes did not differ significantly between sections of the river with or without fish. However, there was a significant difference in community structure in marginal vegetation between sections of river. In sections with M. salmoides several large or conspicuous taxa (Odonata, Hemiptera and Coleoptera) were significantly reduced ( p p Keywords: community structure, conspicuous taxa, invasive predators, predation African Journal of Aquatic Science 2010, 35(3): 273–281
46 citations
TL;DR: March 2002, Water Research Commission, Pretoria, South Africa Ring-bound soft cover, 293 pages WRC Report No.
Abstract: March 2002, Water Research Commission, Pretoria, South Africa Ring-bound soft cover, 293 pages WRC Report No. TT 167/02; ISBN 978-1-86845-827-1; price R100.00 (South Africa), US$50.00 (international) Obtainable from the Water Research Commission, Private Bag X03, Gezina, Pretoria 0031, South Africa; or orders@wrc.org.za
45 citations
TL;DR: Current knowledge of the 85 species in the genus Cichlidogyrus, collected worldwide, including their hosts, localities and authors, is summarised in a table.
Abstract: Current knowledge of the 85 species in the genus Cichlidogyrus, collected worldwide, including their hosts, localities and authors, is summarised in a table. Although these parasites occur mainly in Africa, representatives have been recorded on cichlids in Mexico. Their distribution and host specificity are commented on.
34 citations
TL;DR: The levels of Cu, Fe and Zn in water, sediment and Cynothrissa mento, a commercially important fish species, were investigated from April 2007 to March 2008 at three sites in Ologe Lagoon.
Abstract: The levels of Cu, Fe and Zn in water, sediment and Cynothrissa mento, a commercially important fish species, were investigated from April 2007 to March 2008 at three sites in Ologe Lagoon. Metal levels in the water column and C. mento were lower than the FAO/WHO drinking water and food safety limits. In most cases, metal concentrations were highest during the dry season and lowest in the wet season. Metal concentrations in sediment and C. mento varied significantly among the sampling stations, but in the water column only the levels of Fe and Zn differed significantly between stations. Concentrations of metals in C. mento were significantly affected by wet and dry seasons. The metal concentrations in Ologe Lagoon were lower than the values reported in some Nigerian water bodies. While the Ologe Lagoon system contains the heavy metals studied, their levels in the water, sediment and fish are still within acceptable limits.
29 citations
TL;DR: June 2002, Water Research Commission, Pretoria, South Africa Ring-bound, soft cover, 141 pages WRC Report No.
Abstract: June 2002, Water Research Commission, Pretoria, South Africa Ring-bound, soft cover, 141 pages WRC Report No. TT 182/02; ISBN 978–1-86845875–2; price R100.00 (South Africa), US$50.00 (International) Obtainable from the Water Research Commission, Private Bag X03, Gezina, Pretoria 0031, South Africa. or orders@wrc.org.za
28 citations
TL;DR: The presence of macrophytes and abundant detritus, a food resource for macroinvertebrates, account for their high abundance in shallow waters.
Abstract: Benthic macroinvertebrate community composition was investigated in 2008 at 55 stations at various depths in the nearshore and offshore waters of Lake Victoria, in relation to dissolved oxygen, pH, temperature, chlorophyll a and conductivity. Macroinvertebrate abundance was higher in the shallow nearshore waters than in the deep offshore waters. The communities of the shallow, intermediate and deep environments were composed mainly of molluscs, worms and insects. Gastropods (52.68%) and bivalves (40.18%) constituted the major part of the benthic community. Bellamya unicolor, Melanoides tuberculata and Coelatura spp. were the most abundant molluscs. Various macroinvertebrates showed depth preferences, with gastropods having a strong preference for shallow waters and bivalves a weak preference for deep waters. The present findings contrast with those of most studies done before 1984, but agree with many done after that period. The presence of macrophytes and abundant detritus, a food resource for macroinver...
25 citations
TL;DR: The Mfolozi-Msunduzi estuarine system is dominated by the polychaetes Ceratonereis sp., Dendronereis arborifera and Capitella capitata, the crab Paratylodiplax blephariskios and the tanaid Apseudes digitalis as discussed by the authors.
Abstract: The Mfolozi–Msunduzi estuarine system historically shared a common mouth with the St Lucia estuarine system. In 1952, a separate mouth was created, 1.5 km south of St Lucia mouth, to prevent silt carried by the Mfolozi River from entering Lake St Lucia. Despite its proximity to the comparatively well-studied St Lucia Estuary, there is very little information on the Mfolozi– Msunduzi estuarine system in general and no information on its benthos. In the present study, 17 taxa were recorded from biannual quantitative sampling in 2007 and 2008. Results indicated that the system was dominated by the polychaetes Ceratonereis sp., Dendronereis arborifera and Capitella capitata, the crab Paratylodiplax blephariskios and the tanaid Apseudes digitalis. The main factors influencing the distribution of the benthos were oxygen concentration, temperature, the open or closed state of the mouth, and salinity, with particle size and organic content of the substratum also being important in determining community structure....
22 citations
TL;DR: In this paper, industrial and urban impacts on the lower reaches of the Mvoti River were studied using changes in macroinvertebrate community structures as indicators of environmental change.
Abstract: Industrial and urban impacts on the lower reaches of the Mvoti River were studied using changes in macroinvertebrate community structures as indicators of environmental change. Macroinvertebrates were sampled during high- and low-flows in 2005 in the lower Mvoti River and its tributaries. Uni- and multivariate analyses revealed significant spatial differences between sites on the Mvoti River and those on the tributaries, as well as between sites on the Mvoti above and below the confluences of these tributaries. No significant trends in temporal distributions were recorded. Spatial differentiation was attributed to the abundance of insensitive taxa such as chironimids and oligochaetes at impacted sites. Increased salts and chemical oxygen demand, with lower dissolved oxygen concentrations, were identified as the driving water quality parameters affecting macroinvertebrate community structures. Comparison of macroinvertebrate structures in the Mvoti River with those in the biogeographically similar Mhlathuz...
22 citations
TL;DR: The fish community of the Mfolozi-Msunduzi estuarine system was investigated with particular emphasis on its role as a nursery area for marine fish when the adjacent St Lucia mouth is closed as discussed by the authors.
Abstract: The fish community of the Mfolozi–Msunduzi estuarine system was investigated with particular emphasis on its role as a nursery area for marine fish when the adjacent St Lucia mouth is closed. The mouth was open during March 2007 and 2008 with high-turbidity river water flowing into the sea, and was closed during August 2007 and 2008. Fish were sampled biannually with seine-nets during March and August in 2007 and 2008 at five sites throughout the system. A total of 5 886 fish from 59 species were recorded, with a higher number of species and CPUE in the Mfolozi Estuary than in the Msunduzi Estuary. Seine-net catches were dominated by Ambassis gymcocephalus, Ambassis natalensis, Leiognathus equula and Valamugil cunnesius. Juveniles of marine spawning species were present throughout the study period, even when the mouth was closed. The sampled fish assemblage structure was influenced by significant temporal differences between the four biannual sampling seasons, with relatively small spatial differences bet...
18 citations
TL;DR: In this paper, a three-level hierarchical river and wetland type classifications, based on spatio-temporal scaling relationships, are proposed to provide the foundation for a freshwater conservation plan for KwaZulu-Natal.
Abstract: To provide the foundation for a freshwater conservation plan for KwaZulu-Natal, three-level hierarchical river and wetland type classifications, based on spatio-temporal scaling relationships, are proposed. This resolution of classification is appropriate for regional- or provincial-scale conservation planning. The hierarchical structure of the classifications provides scope for finer resolution, by the addition of further levels, for application at a sub-regional or municipal scale. The proposed classifications include 74 river and 16 wetland types. River typing incorporating a classification based on intra-annual flow patterns from 40 gauging weirs could not be accurately represented spatially. Research on testing the strengths of the relationships among environmental surrogates for biotic diversity is proposed.
16 citations
TL;DR: The history of South African estuarine ichthyology from 1910 to 2010 is reviewed in this paper, where a series of surveys initiated by Day documented fishes in a range of estuaries in KwaZulu-Natal and the Western Cape, but little detailed biological information was collected.
Abstract: The history of South African estuarine ichthyology from 1910–2010 is reviewed. The first survey of fishes in a South African estuary was undertaken by Gilchrist in the early 1900s, followed by an extended period between the two world wars when little or no work was conducted in South African estuaries. In the 1940s and 1950s a series of surveys initiated by Day documented the fishes in a range of estuaries in KwaZulu-Natal and the Western Cape, but little detailed biological information was collected. The estuarine surveys of the 1950s and 1960s were superseded by autecological and synecological studies in the 1970s and 1980s which yielded descriptive and process-orientated information on a wide variety of fish species, including the larval stages of many taxa. This approach continued during the 1990s with publications dealing increasingly with the response of fish assemblages to declining freshwater inflows, the consequences of growing angling pressures on fish populations, and the increasing anthropogen...
TL;DR: Wetland hydrological health and the provision of indirect ecosystem services in the eMthonjeni-Fairview Spring Wetland, Grahamstown, South Africa were assessed in 2008, using the newly developed wetland assessment tools WET-Health and WET -EcoServices as discussed by the authors.
Abstract: Wetland hydrological health and the provision of indirect ecosystem services in the eMthonjeni–Fairview Spring Wetland, Grahamstown, South Africa, were assessed in 2008, using the newly developed wetland assessment tools WET-Health and WET-EcoServices. Variation in health and ecosystem services were assessed over time, based on aerial photograph interpretation and the use of the score sheets in these assessment tools. Hydrological health and indirect ecosystem services of the wetland have been altered since 1949, due to human activities both in the catchment and the wetland. The most significant human intervention on the wetland's hydrological health was the result of road construction and invasion by alien plants. Water use by local residents had an unmeasurable effect on hydrological health. Wetland health is related to the provision of wetland ecosystem services, and cumulative impacts in the catchment and wetland have reduced the provision of many indirect wetland ecosystem services.
TL;DR: In this paper, the Mfolozi and Msunduzi estuarine system is described and anthropogenic impacts, which resulted in the rivers being separated from the St Lucia Estuary and having their own combined mouth to the sea, are detailed.
Abstract: The original structure and functioning of the historical Mfolozi–St Lucia estuarine system are described and anthropogenic impacts, which resulted in the Mfolozi and Msunduzi rivers being separated from the St Lucia Estuary and having their own combined mouth to the sea, are detailed. An overview is provided of the current ecological status of three major faunal groups, zooplankton, benthos and fish, present in the Mfolozi–Msunduzi estuarine system, a system upon which, until recently, virtually no scientific research had been conducted. Currently, decreased rainfall and extended closure of the St Lucia mouth have resulted in this system being under major ecosystem stress. Management options, both short- and long-term, related to reconnecting the Mfolozi–Msunduzi to a common mouth with St Lucia are considered. These include the re-establishment of sediment-filtering swamps in the lower reaches of the Mfolozi and Msunduzi rivers, as well as the construction of levees that would protect the bulk of the adja...
TL;DR: In this paper, the authors investigated the impact of mouth closure on the ecology of the Mfolozi-Msunduzi estuarine system and found that polychaetes were a core benthic group present in the St Lucia system throughout the current drought.
Abstract: The onset of a prolonged drought in the St Lucia catchment in 2002 and subsequent mouth closure raised concern for the biota of the estuary. Ezemvelo KZN Wildlife proposed a scheme whereby the Mfolozi–Msunduzi mouth would be closed, causing fresh water to enter the St Lucia Estuary to prevent excessively hypersaline conditions (>65) from developing in the lower and middle reaches of the St Lucia system. Although this proposal caused concern about the impact of mouth closure on the ecology of the Mfolozi–Msunduzi estuarine system, it raised its potential as a source of benthic fauna dispersal into, and the restocking of, the St Lucia system. Quantitative benthic sampling in the Mfolozi–Msunduzi system in 2007 and 2008 revealed a benthic community generally dominated by polychaetes which, although low in terms of total species richness compared with St Lucia, included elements of a core benthic group present in the St Lucia system throughout the current drought. The presence of the gravimetrically important...
TL;DR: Spatial and seasonal variation in macrozoobenthic composition, abundance and diversity in Aiba Reservoir were investigated bimonthy between June 2004 and April 2005 using a van Veen grab.
Abstract: Spatial and seasonal variation in macrozoobenthic composition, abundance and diversity in Aiba Reservoir were investigated bimonthy between June 2004 and April 2005 using a van Veen grab A depauperate fauna of nine taxa was recorded Generally, larger numbers of taxa were recorded during the dry season than in the wet season Melanoides tuberculata and chironomid larvae dominated the macrozoobenthos and showed wide spatial distribution Diversity and evenness were lower during the wet season than in the dry season, when densities of the major species were low Melanoides tuberculata and chironomid larvae were recorded from maximum depths of 39 m and 26 m, respectively Both taxa were also recorded from all substrate texture types, regardless of the amount of macrophyte material present The benthic fauna is characterised as being poor in terms of density, taxonomic richness and diversity
TL;DR: The Mfolozi Estuary effectively functioned as a temporarily open/ closed type estuary, and the low-flow conditions did not adversely affect the estuarine mesozooplankton, largely because the mouth never remained closed for any extended period.
Abstract: The mesozooplankton of the Mfolozi and Msunduzi estuaries, which share a combined mouth, was sampled twice per year during a two-year period of relatively low river flow. Samples were collected during March, after the rainy season when the estuary mouth was open, and during August, after the low-rainfall winter months when the mouth was closed. The estuarine calanoid copepods Pseudodiaptomus stuhlmanni and Acartia natalensis were numerically dominant, making up 75% of the total number of mesozooplankton recorded. Relatively high abundances were recorded for these copepods, with P. stuhlmanni reaching peak densities of 79 000 individuals m−3. In the low-salinity regions of the estuaries, especially the upper regions of the Msunduzi, the cladoceran Moina sp. also attained high densities, reaching 50 000 individuals m−3. During sampling sessions when the mouth of the estuaries was closed the systems became relatively fresh, in contrast to open-mouth conditions when seawater dominated the lower reaches. Peak ...
TL;DR: In this paper, the authors compared the fish assemblages of mangrove forest patches and adjacent intertidal flats in Ungwana Bay using stake-net sampling in the mangroves forest and inter-tidal flat habitats between December 2002 and November 2003.
Abstract: Fish assemblages of mangrove forest patches and adjacent intertidal flats in Ungwana Bay were compared using stake-net sampling in the mangrove forest and intertidal flat habitats between December 2002 and November 2003. Four forest sites were compared with paired intertidal flat sites with either sand or mud substrata. Distinct ichthyofaunal differences were found between the habitats. Pooled data indicated a significantly higher fish density and biomass in the forests compared to the intertidal flats. Mean fish densities were 0.2–2.7 fish m−2 in the forest and 0.1–2.1 fish m−2 on the flats. Thirty-five species were sampled, eight of which occurred exclusively in the forest and six were limited to the intertidal flats. However, species exclusive to either the forest or intertidal flats contributed <1% towards the total number of fish sampled. Anchoviella commersonii dominated the forest habitat and Pellona ditchela the open intertidal flats. Cluster analysis grouped fish assemblages into two groups, base...
TL;DR: In Senegal, a laboratory study was conducted in 2005 to ascertain the effect that different numbers of the host-specific weevil per plant had on selected plant growth parameters of its target weed, water lettuce.
Abstract: In Senegal, a laboratory study was conducted in 2005 to ascertain the effect that different numbers of the host-specific weevil Neohydronomus affinis Hustache (Coleoptera: Curculionidae) per plant had on selected plant growth parameters of its target weed, water lettuce Pistia stratiotes Linnaeus (Araceae). Compared to the control, the weevil caused a significant reduction in all parameters measured, except for daughter plant production. There were no significant differences in impact on the plant between the three different densities of weevil (one, two and three pairs per plant). Under laboratory conditions one pair per plant is deemed sufficient to effect complete control of water lettuce over a six-week period.
TL;DR: Oocyte diameter frequency distribution suggests synchronous development with a single total spawning in Labeo senegalensis, a highly fecund fish that presents a seasonal cycle of reproduction from May to October during the rainy season.
Abstract: Aspects of the reproductive biology and population structure of Labeo senegalensis were investigated in the Oueme River between April 2005 and March 2006. Reproductive strategy was investigated using gonadosomatic index, ovarian structure and fecundity. Average size-at-first-maturity (L 50) was estimated at 29 cm TL for females and 25.7 cm TL for males. The average sex ratio (1:0.96) was not significantly different from unity. Oocyte diameter frequency distribution suggests synchronous development with a single total spawning. Absolute fecundity ranged between 12 948 and 74 832 eggs. Labeo senegalensisis a highly fecund fish that presents a seasonal cycle of reproduction from May to October during the rainy season.
TL;DR: Mitochondrial DNA markers indicate that this stock known as Dutch catfish, a domesticated strain developed in the Netherlands, is genetically distinct from the natural populations of C. gariepinus in South Africa.
Abstract: Clarias gariepinus, a catfish species widely distributed in Africa including South Africa, is naturally absent from the Western Cape and the coastal Eastern Cape provinces. Because of its potential as an aquaculture species it has been widely used in aquaculture ventures in South Africa, specifically a stock known as Dutch catfish, a domesticated strain developed in the Netherlands. Mitochondrial DNA markers indicate that this stock is genetically distinct from the natural populations of C. gariepinus in South Africa. It could potentially pose a threat to South Africa's natural biodiversity if these fish were to escape from aquaculture farms, or was deliberately introduced into inland waters.
TL;DR: Water quality, macroinvertebrate diversity and fish diversity of the Shingwedzi River system were monitored in 2007/2008 to determine the present status of the system as discussed by the authors.
Abstract: Water quality, macroinvertebrate diversity (using SASS5) and fish diversity (using the fish response assessment index) of the Shingwedzi River system were monitored in 2007/2008 to determine the present status of the system. Possible water pollution sources were identified by aerial survey. Water quality parameters frequently exceeded the threshold of potential concern values set by SANParks. SASS scores were generally low, due mainly to organic pollution as a result of the lack of infrastructure in the catchment. Fish responses indicated a general ecological decline to a ‘category C’ river: moderately modified. Of concern was the absence of some fish species that historically occurred in this system. Sources of pollution such as acid mine drainage from abandoned mines, inadequate sewerage infrastructure and habitat destruction due to siltation and sand mining are discussed.
TL;DR: In this paper, Asian aquatic plant moth Parapoynx diminutalis, accidentally introduced earlier, contributes to control of an aquatic weed Hydrilla verticillata in South Africa.
Abstract: (2010). Asian aquatic plant moth Parapoynx diminutalis, accidentally introduced earlier, contributes to control of an aquatic weed Hydrilla verticillata in South Africa. African Journal of Aquatic Science: Vol. 35, No. 3, pp. 307-311.
TL;DR: In this paper, the authors investigated changes in the fish communi-ties in relation to drought and flooding in four floodplain pans in the Save Valley Conservancy, south-eastern Zimbabwe.
Abstract: Received 11 May 2009, accepted 31 July 2009Temporary floodplain pans in southern Africa are defined as ‘seasonal freshwater palustrine wetlands, up to 2 m deep and with a maximum surface area of 8 ha, adjacent to a well-defined river channel’. They are seasonally or periodi-cally inundated when the river overflows its banks in a flood event, and their substrate is dominated by alluvial or hydric soils (Cowan 1995). Floodplain pans play an important role as refugia and breeding habitats for freshwater fish (Coke and Pott 1971). In southern Africa, extensive floodplains are found on large rivers such as the Zambezi, Kafue, Limpopo and Pongolo (Davies and Day 1998), and, in Zimbabwe, floodplain pans occur in the middle Zambezi (Mana Pools) (Goudie and Thomas 1985) and in the Save–Runde system (Dallas 1998).The hydrological regimes of floodplain pans follow a seasonal pattern of filling up in the wet season and then drying out after the rains end. During the dry season and in periods of extreme drought these pans are totally dry but, as soon as they receive some water, explosive biological activity begins. Early colonisers include insects and birds, which are highly mobile, followed by groups such as gastro-pods, crustaceans, and some amphibians and fish, which all have resting stages that allow them to survive without water (Davies and Day 1998). Most fish species can only colonise the pans once the river has risen sufficiently to connect with them. This study investigated changes in the fish communi-ties in relation to drought and flooding in four floodplain pans in the Save Valley Conservancy, south-eastern Zimbabwe. The pans are situated in the alluvial floodplain of the Save River, which covers approximately 40 km
TL;DR: The zooplankton of freshwater-rich estuaries is essentially a subset of the community found in freshwater-starved estuary, and a reducing supply of fresh water leads to estuarine mesozooplanka communities moving along a trajectory of increasing species richness, but decreasing variance and dominance within assemblages.
Abstract: Structure and pattern of mesozooplankton in three tidal estuaries experiencing contrasting salinity gradients were investigated. In the Kariega Estuary, where freshwater inflow was persistently low with little variation in flow, salinity values exceeded 28–30 for long periods (years) throughout the estuary. In the Keiskamma and Great Fish estuaries intermittent floods, coupled to strong and variable baseflows, ensured spatial and temporal variability in salinity distribution. Copepods numerically dominated the zooplankton (95–97%) in all three estuaries. Species richness in the freshwater-starved Kariega Estuary exceeded 35, coupled with reduced variance in abundance and low species dominance at most sites along the estuary. By contrast, the Keiskamma and Great Fish estuaries had relatively few species (21 and 20, respectively), high population variance and high species dominance at most sites. Two mesozooplankton species emerged as possible indicators of freshwater-rich and freshwater-starved estuaries. The copepod Pseudodiaptomus hessei was particularly abundant in the Keiskamma and Great Fish, following the pattern recorded for other estuaries with strong horizontal salinity gradients (>28). By contrast, population density of P. hessei was orders of magnitude lower in the marine-dominated Kariega. The copepod Tortanus capensis was present only in the Kariega Estuary. Characteristically, T. capensis favours upper estuarine reaches or sheltered marine embayments where salinity values consistently remain above c. 33–34 for long periods (months to years). The zooplankton of freshwater-rich estuaries is essentially a subset of the community found in freshwater-starved estuaries, and a reducing supply of fresh water to estuaries leads to estuarine mesozooplankton communities moving along a trajectory of increasing species richness, but decreasing variance and dominance within assemblages. African Journal of Aquatic Science 2010, 35(2): 173–184
TL;DR: The bacterial content of water in the Nyl River System and its possible origins were assessed at five sites between April 2001 and July 2002 and the water was analysed for bacterial counts using standard procedures as mentioned in this paper.
Abstract: Because water quantity and quality are of great importance in the arid Limpopo province, the bacterial content of water in the Nyl River System and its possible origins were assessed at five sites. Quarterly surveys took place between April 2001 and July 2002 and the water was analysed for bacterial counts using standard procedures. Heterotrophic plate counts, faecal coliform counts and total coliform counts indicated that the system was stressed. The Modimolle sewage treatment works and local agricultural activities were found to be the point and diffuse sources of bacterial contamination, respectively.
TL;DR: In this paper, the concentrations of metals in bottom sediment in the Tanzanian waters of Lake Victoria and the nature of suspended particulate matter (SPM) were analyzed and the potential to distinguish between different origins of metal in the lake, if the sources of SPM are well construed, is demonstrated.
Abstract: The concentrations of metals in bottom sediment in the Tanzanian waters of Lake Victoria and the nature of suspended particulate matter (SPM) were analysed. The objective of the study was to compare levels of metals in sediment from different locations and to establish their sources. Metal concentrations were higher in sediment in locations within urban catchments. There were significant differences between sites for concentrations of Cu, Cr, Zn, Hg and Pb in sediment. Mercury concentration was higher in Nungwe Bay sediment compared to other areas, and Cr was higher in Magu Bay, while Cu, Pb and Zn were higher in Mwanza Gulf. Watershed characteristics such as urbanisation, and lake characteristics such as algal biomass, influence the nature of SPM, and hence the concentration of metals in the sediment. The potential to distinguish between different origins of metals in the lake, if the sources of SPM are well construed, is demonstrated.
TL;DR: Investigation of the potential molluscicidal activity of five Nigerian plant species used in alternative medicine practice as anthelmintics found that egg masses and adult snails were most susceptible to D. sissoo fruit extract and least susceptible to V. amygdalina leaf extract, but further studies are recommended on the ethanolic extracts of A. senegalensis, A. leiocarpus, C. retusa and V. AmygdalINA.
Abstract: Laboratory studies were conducted to determine the potential molluscicidal activity of five Nigerian plant species used in alternative medicine practice as anthelmintics. Laboratory-bred adult Biomphalaria pfeifferi, the snail host of Schistosoma mansoni in Nigeria, and their viable 0- to 24-hour-old egg masses were separately exposed for 24 hours, in replicated bioassays, to 7.81–4 000 mg l−1 concentrations of crude ethanolic extracts of the leaves and roots of Annona senegalensis, Anogeissus leiocarpus, Crotalaria retusa, Dalbergia sissoo and Vernonia amygdalina. Fruits and stem bark of D. sissoo were also investigated. The 24-hour LC50 and LC90 values of extracts for target organisms were calculated using probit analysis. Susceptibility of target organisms to extracts varied with the plant species and morphological part. Egg masses and adult snails were most susceptible to D. sissoo fruit extract (LC90 values of 89.29 and 74.33 mg l−1, respectively) and least susceptible to V. amygdalina leaf extract (...
TL;DR: In this paper, the speciation of cadmium, lead, copper, zinc, manganese and iron into exchangeable, carbonate, reducible and organic bound fractions was studied in sediments from coastal and freshwater environments in Ghana.
Abstract: The speciation of cadmium, lead, copper, zinc, manganese and iron into exchangeable, carbonate, reducible and organic bound fractions was studied in sediments from coastal and freshwater environments in Ghana. This was relevant as the species in which metals are stored within specific sediment components is important in determining their impact on the environment. For both coastal and inland sediments, a higher percentage of cadmium was associated with the more available exchangeable and carbonate fractions, while iron, zinc and manganese were mainly associated with the reducible and organic fractions. Lead and copper were found to have the greatest ability to form different species in the samples examined and were more evenly associated with all the fractions. The metals generally showed more ability to form different species in inland freshwaters than in coastal relatively saline waters. However, differences between inland and coastal waters were based more on whether the environments were oxidising or ...
TL;DR: The feeding ecology of the caridean shrimp Palaemon peringueyi in the temporarily open/closed Kasouga Estuary, Eastern Cape, was examined during summer and winter employing stomach fullness index (SFI) analysis, finding no significant differences in the SFI values between males and females.
Abstract: The feeding ecology of the caridean shrimp Palaemon peringueyi in the temporarily open/closed Kasouga Estuary, Eastern Cape, was examined during summer and winter employing stomach fullness index (SFI) analysis. Mean SFI values for male and female shrimp during summer ranged from 0.85% to 2.36% and from 0.56% and 2.61% body dry weight, respectively. During winter, SFI values for males and females were lower, and varied between 0.23% and 1.56% and 0.36% and 1.84% body dry weight, respectively. There were no significant differences in the SFI values between males and females during the two seasons. A peak in the feeding activity for both sexes was observed during the daytime during both summer and winter. For both males and females, non-linear regression analysis best explained the change in SFI over time. The gut evacuation rate constants (k) of males and females during summer were estimated at 0.43 h−1 and 0.30 h−1, respectively. These values correspond to a daily food intake equivalent to 16.2% body dwt ...